Dry contact type electrically asymmetric device



Sept.27, 1949. E. A. RICHARDS ETAL 2,482,799

DRY CONTACT TYPE ELECTRICALLY ASYMMETRIC DEVICE Filed Dec. 1:5, 1946 A llorney Ritented Sept. 27, 1949 DRY CONTACT TYPE ELECTRICALLY ASYIVIMIETRIC DEVICE Edward Arthur Richards and Leslie James Ellison, London, England, assignors to International Standard Electric Corporation, New

York, N. Y.

Application December 13, 1946, Serial No. 716,158 In Great Britain December 21, 1945 1 Claim. (Cl. 175-366) This invention relates to the construction of electrically asymmetric devices such as rectifiers, photo-electric cells and thermo-couples of the dry contact type and more particularly to the construction of elements for such purposes which comprise a base plate, coated with a layer of semi-conductor such as selenium, to which is applied a counter-electrode.

One conventional form of element consists in a plate having a hole through which an insulated mounting rod is passed to enable contacts and terminals to be clamped to the electrodes of the element. In another conventional form the element is placed in a container, terminals on the outside thereof leading through the container to arrangements inside which make the necessary contacts with the electrodes of the element.

One object of the invention is to provide a unit plate type element which is readily connected into a. circuit or is readily connected to another such element.

Another object of the invention consists in providing an element having an easily and accurately regulated working area, free from contact or assembly pressure, with terminals of simple construction. Yet another object of the invention is to provide an element which can be used singly or in bridge or other assemblies.

According to one feature of the present invention a dry contact type electrically asymmetric e ementcomprises two electrodes and terminals for said electrodes afiixed outside the working area.

According to another feature of the invention a dry contact type electrically asymmetric element comprises a base plate having an'area larger than the active area of the element, a semi-conductor layer covering said base plate area, a layer of insulating material defining said active area, and holes in said base plate and said as in radio and communication equipments and circuits.

The invention will be better understood from the following detailed description, taken in conjunction with the accompanying drawings in which- Figures 1 and 2 show a plan view and sectional elevation respectively of a selenium rectifier element embodying the invention:

Figures 3 and 4 are similar views of embodiment of the invention; and

Figure 5 shows a plan view of an assembly of elements forming a full wave rectifier.

In Figures 1 and 2, l represents a base plate on which a layer of semi-conducting material 2, e. g. selenium is applied by any well known method. A layer of insulating material 3, consisting of paint, lacquer, paper or any siutable material which can be caused to adhere to the surface of the semi-conductor, covers the surface of the layer 2, leaving exposed the working surface ll. 4 is a layer of counter-electrode material, covering the surface II and having an extension l2 towards one end of the element. The layers l, 2, 3 contain two holes l3, it which can be made at any suitable stage in the manufacture of the element, through which pass tubular extensions 6 and 9 of two terminals 5 and 8 respectively. Terminal 8 makes contact with the counter-electrode metal extension I! and is insulated from the base plate I by an insulating bush l0 through which the extension 9 passes. The end of extension 9 is bent, swaged or spun over the outside of bush l0 and a washer Hi to secure the terminal 8 and bush III in position. At the hole l3 terminal 5 is similarly secured but with an insulating bush I6 inserted for the another topside, the terminal making contact with base layers, through which terminals are afilxed, one

of said terminals having electrical connection with said base plate and another of said terminals having electrical connection with a counter electrode which extends over said active area.

According to yet another feature of the invention the terminals of such an element are symmetrically positioned while the counter electrode is unsymmetrically positioned with relation to the working area.

The invention is particularly applicable where y it is desired that the element shall be compact and easily mounted or suspended by its connections and have a relatively small working area plate I through washer 1. In Figures 3 and 4 the insulating layer 3 only extends around the hole I4 and the working area is controlled by limiting the area of'the counter-electrode 4 by masking or other suitable means. Terminal 8 is secured as before, making contact with extension ll of the counter-electrode over the insulating layer 3. Terminal 5 is insulated from the selenium surface by insulating washer I6 and is secured as before.

Instead of providing the terminals with tubular extensions, the terminals may be afilxed by solid rivets insulated in the same way.

Elements of thekind described can be assembled to form a full wave rectifier as shown in plan view, Figure 5. Four elements laid together as shown and firmly fixed together through their of the invention.

holes by soft rivets l'i make the necessary contacts with one another and, through the rivets,

' port and in fact to carry the weight of other small parts which are sometimes used in radio and other circuits.

While the invention has been described in relation to a, rectangular element with rounded 15 tegrally with the heads thereof, within said insulative sleeves, the ends of said rivets remote from ends as shown in the drawings, its application is not limited to such a shape and an element may beof any desired suitable shape. Moreover. the

terminals may be at the same edge or at adjacent edges of the element without exceeding the scope What is claimed is:

- A dry contact type electrically asymmetric eiementthat comprises: an elongate'flat metallic base element having a pair of openings formed therein, one b ng located near each end thereof:

a layerot semi-conductive material overlying' the top surface of said base-element; an electrically insulative coating covering the exposed top sur-' face of the semi-conductive layer with the ex-' ception of a relatively small localized area spaced 30 from and located intermediate the openings formed in. the base element; a counter-electrode 1 on said insulative coating, positioned around marginal portions a first but not the second. of

said pair 'of openings in the base element and 35 2,414,471

making contact with the semi-conductive-layer throughout the exposed localized area not covered by the insulative coating; a pair of electrically insulative sleeves, each having a flange integrally formed on one end thereof, positioned within and extending through said openings in a, manner such that the flange or the sleeve in the said first opening overlies a portion or the bottom surface of the base element at the margin 10 of the opening, and the flange of the sleeve in the said second opening overlies a portion of the insulative coating on the semi-conductive layer at the margin of the opening; a pair of rivet elements having radially extending lugs formed inthe heads" being provided with metallic washers and being bent over said washers whereby the second opening is connected with the base element.

EDWARD ARTHUR RICHARDS.

LESLIE JALIIES ELLISON.

REFERENCES crr n The following references'are of record in the file of this patent:

' UNITED STATES PATENTS 'Number Name Date 2,172,200 Hein Sept. 5, 1939 2,213,388 Dormo'y et 81. Sept. 3, 1940 2,386,218 Kotterman' (A) Oct. 9, 1945 Kotterm'an (B) Jan. 21, 1947 

